The conventional motor bushing structure is as shown in the Taiwan Patent Publication No. 591860 “Bushing assembly structure of motor”.
Please refer to FIG. 1 showing a motor shaft tube assembly structure, which includes a hub 1, thereon disposed a shaft tube 11, a fastener 2 and a bushing 14. The shaft tube 11 has a shaft hole and annular wall corresponding to the stator set 3. The fastener 2 contains a cap 21, several arms 22 and several barbs 23. The arm 22 extends from the top of the cap 21 and the barb 23 is formed on the top side of the arm 22. The shaft tube 14 is disposed inside the fastener 2 and contains a bearing 4 therein. When the bushing 14 and the fastener 2 are disposed inside the shaft tube 11, the fastener 2 is utilized to clasp the stationary stator set 3 by means of the barb 23 of the arm 22 and to inwardly hold the bushing 14 by means of the arm 22 so that the bushing 14 is tightly integrated with the bearing 4, allowing the shaft 51 of the rotor 5 to penetrate through the bearing 4 and rotate therein.
Notwithstanding, the structure design of the aforementioned prior art has its own limit. For instance, before a snap ring 52 is inserted between the base 141 of the shaft tube 14 and the cap 21 of the fastener 2, the snap ring 52 shall be fitted in the stairs of the cap 21 of the fastener 2 and then the bushing 14 is placed inside the fastener 2 such that the snap ring 52 can be fastened and positioned when the bushing 14 is held by the arm 22 of the fastener 2.
However, such assembling method is not very convenient. During the course of placing the bushing 14 in the fastener 2, care shall be taken constantly concerning if the snap ring 52 falls off the stairs 25, easily resulting in the failure upon engaging and positioning the shaft 51 and the rotor 5 as well as the inferior quality. Normally, such assembling issue is hard to be controlled.